Condensing units are often mounted on rails with
flexible suction and liquid lines to permit sliding the
condensing unit out of the bus body to aid in servicing.
Air-cooled condensers are used. Thermostatic
expansion valve refrigerant controls are standard.
Finned blower evaporators are also used.
The duct system usually runs between a false
ceiling and the roof of the bus. The ducts, usually one
on each side of the bus, have grilles at the passenger
seats. The passengers may control the grille by opening
The Environmental Protection Agency (EPA) has
established as per the Clean Air Act (CAA) that all
technicians who maintain or repair air-conditioning or
refrigeration equipment or technicians who operate
recycling, reclaiming, and recovery equipment must
be certified. Certification is administered by
organizations with certification programs that are
approved by the EPA. It is important to understand,
that as a Utilitiesman, if you are not certified, you
cannot do any HVAC/R service that requires use or
removal of refrigerants. Certification requirements are
divided into two different areasautomotive
air-conditioning and HVAC/R.
Automotive Air-Conditioning Certification
Automotive air conditioning is serviced or
r e p a i r e d m o r e o f t e n t h a n o t h e r t y p e s o f
air-conditioning systems. In today's world,
automotive air-conditioning systems are heavily used
as our society spends more and more time in their
vehicles. Industry experts say that 25 percent of the
R-12 purchased in the United States is used in
automotive air conditioning. The fittings and hoses
used in automotive air conditioning allow leakage to
occur. Automotive air-conditioning service facilities
or technicians are now changing (retrofitting) systems
in vehicles to use refrigerant R-134a and removing
CFC R-12 to meet new standards. From the EPAs
standpoint, technicians must be meet the following
requirements to be certified:
Be aware that venting refrigerant is illegal.
Understand why all the regulations are being
created. Understand what is happening to the
Have a working knowledge of SAE standards
J-1989, J-1990, and J-1991.
Perform service in a safe manner without
injuring personnel or damaging equipment.
Areas that must be understood include venting,
handling, transporting, and disposing of
Once these requirements are met through testing of
the individual applicant, a certification card is issued.
Heating, Ventilating, Air Conditioning, and
Certification requirements to service standard
types of air-conditioning systems are the same as for
automotive air-conditioning certification. Unlike the
automotive certification program, standard
air-conditioning certification is divided into levels
corresponding to the type of service the technician
performs. There are four types of certification:
Type I Servicing small appliances
Type II Servicing high or very high-pressure
Type III Servicing or disposing of
Type IV (Universal) Servicing all types of
Individuals will be required to take a proctored,
closed book test. These tests are offered by
organizations approved by the EPA for the specific
type of certification that the individual technician
r e q u i r e s . T e c h n i c i a n s c a n o n l y w o r k o n
air-conditioning systems that they have been certified
The saturation temperature increases or
decreases depending upon what factor?
What are the three basic types of automotive
A scotch-yoke compressor changes rotary
motion into what type of motion?
Refrigerant can be put into a system when the
service valve is back-seated. True /False
The POA valve, receiver-drier, expansion valve,
and sight glass are combined in what type of
Service procedures for VIR systems are different
than conventional automotive air-conditioning